In many automotive applications, it is highly desirable to know wheel or half-shaft torques. One such application is transmission shift control. Knowledge of wheel or axial torque is a key factor for proper synchronization. Another automotive application benefitting from knowledge of wheel torque is drive traction control.
Existing methods and systems for estimating and/or measuring torque utilize costly hardware, such as torque sensors, and provide estimates that are inaccurate. For example, U.S. Pat. No. 3,921,446, issued to Ludloff, discloses a method for individual torque determinations in systems with multiple torques acting collectively and independently, based on angular velocity and angular acceleration. Preferably, the particular relation for a subsystem torque is known in terms of both the system torque and other subsystem torques and involves a plurality of independent subsystem torques. The method includes the steps of making M independent torque determinations at a particular angular velocity, each of the torque determinations being established under operating conditions which ensure independence of the M torque determinations. The method also includes the steps of combining the torque determinations according to a known relation so as to isolate subsystem torque contributions and making the established torque available for further use.
Other United States patents involving torque estimations include U.S. Pat. Nos. 4,771,848, issued to Namba et al., 5,010,866, issued to Ohata, 5,046,176, issued to Lin and 5,101,786, issued to Kamio et al.
Due to the expense and inaccuracies associated with the existing systems and methods, it is desirable to estimate a single torque quantity, such as wheel torque, utilizing multiple models. Such a method of torque estimation would eliminate most of the inevitable inaccuracies characterizing single-model methods.